All communication equipment have to use antenna to receive and transmit signals. Usually, the impedance of a reception or transmission terminal is designed with an impedance ranging from 50 to 75 ohms (which varies according to the design of a specific instrument); the aforesaid impedance value is quite different from the impedance (over 377 ohms) of the free space, and therefore the matching result is poor. In order to obtain a better result an antenna has to be used for a better impedance match and for a better signal strength. If the antenna of an equipment is not properly designed, the poor impedance match would cause the signal to experience a considerable amount of fading; in other words, the design of an antenna is quite important to a communication equipment; a properly designed antenna can have the characteristics of an equipment performed fully, i.e., to have a signal reached a faraway place. Otherwise, an equipment would be unable to show its functions, or even to shorten its serviceable life. Usually, the function of an antenna is limited by terrain feature and buildings, and therefore it has to be turned and adjusted in the direction facing the transmitter. Such adjustment would result in an inconvenience to a long pole-shaped antenna, which is usually an extension type and bendable to facilitate storage; however, its complex structure would cause a higher manufacturing cost.